Harper's Island is an American horror mystery limited series created by Ari Schlossberg for CBS. Schlossberg, Jeffrey Jackson Bell and Jon Turteltaub served as executive producers. The series features an ensemble cast led by Elaine Cassidy alongside Christopher Gorham, Katie Cassidy, Cameron Richardson, Adam Campbell, C.J. Thomason, and Jim Beaver. The plot follows a group of family and friends that travel to the titular locale for a destination wedding, only to learn that there is a killer among them. At the center of the mystery is Abby Mills (Elaine Cassidy), whose mother was one of several people murdered by John Wakefield seven years prior.

The series premiered on April 9, 2009, and was marketed as a thirteen-week limited event. The final two episodes aired on July 11. By the end of its run, Harper's Island averaged 9.36 million viewers, ranking #50 in Nielsen ratings. The first three episodes aired on Thursdays, but was moved to Saturdays during the week of April 28. Because of this, Global Television Network premiered the following episodes two days prior to the United States.

The series was initially intended to be an anthology series featuring a new setting and characters in the second season. However, on July 14, 2009, CBS cancelled the series after one season. The show gained a strong cult following since its release, with some critics and fans noting it as being ahead of its time.